Regeneration of rat submandibular glands following partial extripation of the gland apparently has not been seen to go to full completion. The appearance of the normal numbers of mature granular duct cells was not reported in any of the studies. One possible explanation is that the experiments were not extended an adequate length of time in order to make the observation. Another is that complete regeneration doesn't take place. These proposed experiments will hopefully give more information about the regenerative ability of salivary glands. A portion of the left submandibular gland will be removed from each experimental animal. Isoproterenol will be given to one group of rats after surgery to see if complete regeneration can be achieved and/or speeded up. Testosterone will be given to another group following surgery and its effects will be observed. A third group will be given both isoproterenol and testosterone after surgery. Appropriate controls will be run with each group. Effects of the agents on the glands will be studied using histologic, histochemical, morphometric, and electron microscopic techniques. The rate of appearance of mature parenchymal cells will be monitored. Their numbers will be counted and compared to known well documented adult values as well as control values. Because of the need for normal functioning salivary gland tissue, this type of experimentation has both clinical and biological significance. Furthermore, isoproterenol and testosterone have been shown to have profound effects of developing and mature rat submandibular gland morphology, histochemistry, and biochemistry. Therefore, it is expected that administration of either or both or these agents will cause significant change in regeneration of rat submandibular glands following partial extirpation.